ON THE INFLUENCE OF TURBULENCE ON THE INITIATION OF SEDIMENT MOTION
摘要
For the initiation of sediment motion a theory is developed, which presupposes that the critical shear stress τc responsible for inducing motion in non-turbulent flow is solely defined by the angle of internal friction φ or the angle of repose φ' of single grains. In turbulent flow, fluctuations τ' in the shear stress as well as lift forces produced by these fluctuations also occur. Owing to this, the actual (effective) critical shear stress τ + τ' acting on a grain is larger than the average stress τ on the one hand, and on the other hand, the effective weight of the grains is reduced: they become effectively lighter. On the basis of the presented analytical formulation the initiation of sediment motion may be described solely by the angle of repose of the grains and turbulence parameters.